Cacophony are group based around the guitar antics of Marty Friedman and Jason Becker, two world renown guitarists, in both skill and inspiration. I've only heard their second album Go Off!, which is an excellent chunk of classically-influenced metal, and I look forward to hearing Speed Metal Symphony, a fan favorite.
The majority of Go Off! is based around the speed metal, shred, or neoclassical sound; Friedman and Becker favor exotic guitar scales for many of the songs and, as a result, I've seen some people claim that the music is relatively hard to get into. Personally, I don't find that the case at all because Cacophony's music is extremely engaging, memorable, and adventurous. It sounds fresh each time I listen to it, and I always discover something new to enjoy.
The specific song from Go Off! that I want to highlight is "Sword of the Warrior." As with every song on the album, there is excellent, jaw-dropping lead guitar work, but, most importantly, the riffs kick a lot of butt. Similarly, the overall atmosphere of the song is frenzied, and perfect for envisioning the sword wielder that the band had in mind. I'm not sure if this is the best song on the album, but it certainly presents an awfully enticing example of prime metal riffage.
Cacophony - "Sword of the Warrior"